Disposable guarded finger scalpel for inserting a line in a patient and blade therefor

ABSTRACT

A kit for installing a central line in a patient includes a guarded finger scalpel, a needle with a guide wire, and a catheter. The guarded finger scalpel has a blade with a relatively blunt tip, thereby avoiding an accidental or inadvertent cut or nick of the patient&#39;s vein in the process of enlarging the puncture in the patient&#39;s skin previously made by needle.

CROSS REFERENCE TO RELATED APPLICATIONS

The present invention constitutes a continuation-in-part of applicationSer. No. 08/287,123 filed Aug. 8, 1994 and issued on Aug. 13, 1996 U.S.Letter Pat. No. 5,545,175 which, in turn, is a continuation-in-part ofapplication Ser. No. 08/079,985 filed Jun. 18, 1993 and issued on Dec.6, 1994 as U.S. Pat. No. 5,370,654, the disclosures of which areincorporated herein in their entirety.

FIELD OF THE INVENTION

The present invention relates to a finger scalpel for making a small cutor incision in a patient's skin to facilitate insertion of a catheter,and more particularly, to a guarded finger scalpel to preventinadvertent or accidental nicks or cuts incurred by any of the healthcare providers involved in using the finger scalpel or in the subsequentclean up and disposal thereof.

BACKGROUND OF THE INVENTION

In the process of establishing a line in a patient (as for example,during a heart bypass operation) a catheter is inserted into thepatient. The purpose of the catheter may be to position a sensor orother device within the patient or to inject a medication or a dye intothe patient. In order to insert the catheter, it is first necessary toinsert a guide wire through the patient's skin and to locate one of thepatient's veins (or other vessel, body cavity or organ). The guide wirecomprises a flexible cable which is inserted through a puncture in thepatient's skin, the puncture being made by a needle. Since the punctureis relatively small compared to the catheter, and since the catheter isrelatively soft and flexible and may bend, it is necessary to enlargethe puncture by making a small incision or cut substantially at thepuncture or adjacent thereto.

This relatively small cut is made by a finger scalpel. The fingerscalpel comprises a surgical blade attached to a small plastic handlethat is grasped, typically, between the surgeon's thumb and forefinger.

After the cut is made, the surgeon merely drops the finger scalpel onthe tray or on the patient's gurney. Since the blade is exposed (andusually contains blood or bodily fluids) this is a hazardous situation.The danger occurs in using the finger scalpel, or in cleaning up theoperating room or patient's room, or in subsequent disposal of the usedscalpel.

Accidental or inadvertent contact with the unguarded finger scalpeloften results in the health care provider being nicked or cut, andexposure with the blood or bodily fluids on the blade may result in thehealth care provider sero-converting and thus becoming infected withHepatitis B or the deadly HIV ("AIDS") virus.

Even if an infection does not occur, repeated testing and observation isnecessary whenever a known AIDS patient is involved. This testing isworrisome, inconvenient and costly.

Conversely, there is also a risk to the patient in the event the surgeonor other health care provider is infected with AIDS or any contagiousdisease.

While no specific data is available with regard to finger scalpels, therisk is at least comparable to the problems associated with needlesticks. A study was made by the Needle Stick Surveillance Group of theC.D.C. (Centers for Disease Control). Out of 3,978 needle sticks frompatients known to be HIV positive, 13 health care workers becameinfected--roughly 1 out of 300. Thus, from a single needle stick whiletreating an AIDS patient in an operating room or other environment, thechances are roughly 1 out of 300 that the surgeon, nurse or otherindividual health care provider will sero-convert and become HIVpositive.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide aguarded finger scalpel which substantially eliminates inadvertent oraccidental contact with the blade, thereby preventing the spread ofinfectious diseases.

It is another object of the present invention to provide a guardedfinger scalpel having a retracted blade; such that when the scalpel isgrasped or squeezed between the surgeon's thumb and forefinger, theblade is advanced and exposed for use; and such that when the scalpel isreleased, the blade is automatically retracted to its original positionand is thereby guarded against accidental or inadvertent contact.

It is a further object of the present invention to provide a lock-offmeans to prevent movement of the blade relative to the guard followinguse of the guarded finger scalpel during a surgical procedure, therebypreventing accidental nicks or cuts during clean-up.

In accordance with the teachings of the present invention, the guardedfinger scalpel includes a body normally grasped between a surgeon'sthumb and forefinger. This body includes a blade guide means having aforward portion provided with an opening formed therein. A blade isslidably guided within the blade guide means and has respective sides. Apair of spring arms are connected to the blade and extend laterally ofthe blade on respective sides thereof. These spring arms are manuallysqueezed towards each other, thereby advancing the blade outwardlythrough the opening in the forward portion of the blade guide means inthe body. Conversely, the blade is automatically retracted within thebody when the spring arms are released to return to their originalposition.

In one embodiment, the body comprises a substantially rectangular framehaving top and bottom walls and side portions provided with respectiveopenings formed therein; the spring arms extend laterally through theopenings, respectively, and are confined by the top and bottom walls ofthe frame.

In another embodiment, the body is substantially resilient and hasrespective side walls, and the respective spring arms are confinedwithin the resilient body and engage the respective side walls thereof.With this arrangement, the respective side walls of the resilient bodymay be squeezed together to thereby deflect the spring arms towards eachother.

Viewed in another aspect, the present invention constitutes animprovement in the method of inserting a line in a patient, wherein aneedle is used to make a puncture in the patient's skin to locate a vein(or other vessel, cavity or organ) in the patient. A guide wire isinserted through the needle and through the puncture and into thepatient, and the needle is removed. A catheter is inserted over theguide wire and into the patient, the wire being removed when thecatheter is installed. The improvement includes the steps of providing aguarded finger scalpel having a covered blade, manually grasping theguarded finger scalpel and advancing the blade, making a cut in thepatient's skin substantially at the puncture before the catheter isinserted over the guide wire, thereby facilitating inserting of thecatheter, and automatically retracting the blade within the guardedfinger scalpel, thereby preventing nicks or cuts due to accidental orinadvertent contact with the scalpel during use, clean-up or disposalthereof.

Viewed in still anther aspect, the present invention provides a fingerscalpel for use by a surgeon in installing a line in a patient in ahospital, wherein the finger scalpel is part of a disposable kit, andwherein the finger scalpel includes a body normally intended to begrasped between the surgeon's thumb and forefinger, the body having ablade mounted thereon. In accordance with the teachings of the presentinvention, a guard is provided on the body. The guard has a normalposition covering the blade and preventing accidental contact therewith.A resilient means maintains the guard in the normal position thereof,such that the resilient means may be manually opposed as the fingerscalpel is grasped by the surgeon, thereby exposing the blade relativeto the guard. A lock-off means independent of the resilient means isprovided. The lock-off means is operative in the normal position of theguard and prevents blade exposure, such that the clean-up personnel inthe hospital are protected against nicks or cuts during disposal of thekit.

In a preferred embodiment, the lock-off means includes a lock-off buttoncarried transversely by one of the side walls of the frame.

The inner member within the frame has a pocket formed therein. Thelock-off button may be pushed inwardly of the frame and received withinthe pocket in the inner member, thereby locking the inner member to theframe and preventing relative sliding movement therebetween.

In another embodiment, the look-off button is carried on a depressibletang formed on the one side wall of the frame.

The present invention also provides an improved kit for installing acentral line in a patient. The kit includes, in combination, a needlefor making a puncture in the patient's skin above one of the veins, acatheter with a guide wire, and a guarded finger scalpel having a bladeattached thereto for enlarging the puncture in the patient's skin. Aguard means on the guarded finger scalpel has a normal position in whichthe blade is covered and further has a retracted position in which theblade is exposed. Thus, the guard means is actively disarmed and movedfrom its normal position into it retracted position when the guardedfinger scalpel is grasped, and the guard means is passively armed andreturned to its normal position when the guarded finger scalpel isreleased. Moreover, the blade includes a tip portion having a front edgeand a lower edge forming an acute angle therebetween, and this acuteangle is sufficiently large to prevent the blade from cutting into thevein adjacent to the puncture in the patient's skin.

This acute angle is greater than 45° and, in a preferred embodiment, isapproximately 60°.

These and other objects of the present invention will become apparentfrom a reading of the following specification taken in conjunction withthe enclosed drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of the guarded fingerscalpel of the present invention.

FIG. 2 is a cross-sectional view thereof, taken along the lines 2--2 ofFIG. 1, and showing the respective spring arms connected to the blade,and further showing the spring arms extending through respectiveopenings formed in the side portions of the rectangular frame.

FIG. 3 is a cross-sectional view thereof, taken along the lines 3--3 ofFIG. 2, and showing the blade within the blade guide means.

FIG. 4 is a pictorial view showing the guarded finger scalpel beinggrasped by the surgeon.

FIG. 5 is a further pictorial view, corresponding substantially to FIG.4, but showing the respective spring arms of the guarded finger scalpelbeing squeezed between the surgeon's thumb and forefinger to advance theblade out of the blade guide means.

FIG. 6 is an exploded perspective view, showing the assembly of thecomponents of the guarded finger scalpel of FIG. 1.

FIG. 7 is a side elevation of a second embodiment of the guarded fingerscalpel of the present invention with certain parts thereof broken awayand sectioned to show the blade fully retracted within the body of theguarded finger scalpel.

FIG. 8 corresponds substantially to FIG. 7, but shows the resilient bodyof the guarded finger scalpel being squeezed between the surgeon's thumband forefinger to advance the blade through an opening in the body ofthe guarded finger scalpel.

FIG. 9 is a top plan view corresponding to FIG. 7, with certain partsbroken away, and showing a pair of spring arms connected betweenrespective side portions of the blade and the resilient body of theguarded finger scalpel.

FIG. 10 is a further top plan view with certain parts broken away andsectioned, corresponding substantially to FIG. 9, but showing the bodysqueezed to deflect the spring arms to extend the blade.

FIGS. 11-21 are pictorial views showing the sequence of using theguarded finger scalpel to make a cut (or cuts) in the patient to enablea catheter to be inserted into the patient.

FIG. 11 shows the needle making a puncture in the patient's skin tolocate a vein, and further shows (in exploded relationship thereto) aflexible guide wire about to be inserted into the needle.

FIG. 12 shows the guide wire inserted into the vein, and further showsthe needle being withdrawn therefrom.

FIG. 13 is a cross-sectional view thereof, taken along the lines 13--13of FIG. 12, and drawn to an enlarged scale.

FIG. 14 shows the scalpel being picked up by the surgeon.

FIG. 15 shows the resilient body of the scalpel being squeezed betweenthe surgeon's thumb and forefinger to thereby advance the blade out ofthe body of the guarded finger scalpel.

FIG. 16 shows the blade being used to make a small cut (or cuts) at thepuncture in the patient's skin or substantially adjacent thereto,thereby enlarging the puncture to facilitate insertion of the catheter.

FIG. 17 shows the guarded finger scalpel being released to automaticallyretract the blade.

FIG. 18 shows the catheter being inserted over the guide wire,concentrically thereof.

FIG. 19 shows the catheter being inserted through the cut and into thepatient's vein.

FIG. 20 is a cross-sectional view thereof, taken along the liens 20--20of FIG. 19, and drawn to an enlarged scale.

FIG. 21 is a further cross-sectional view, corresponding substantiallyto FIG. 20, but showing the guide wire being withdrawn from the catheterin the patient's vein.

FIG. 22 is a schematic block diagram showing the preferred method ofusing the guarded finger scalpel of the present invention.

FIG. 23 is a perspective view of a further embodiment of the presentinvention, wherein a lock-off means is provided to lock the blade in itsretracted position and prevent further movement of the blade relative tothe guard on the frame.

FIG. 24 is a portion of FIG. 23, drawn to an enlarged scale, and showinga lock-off button on the frame.

FIG. 25 is a cross-sectional view thereof, taken along the liens 25--25of FIG. 24 and drawn to an enlarged scale, and showing the pocket formedwithin the inner member.

FIG. 26 is a further cross-sectional view, corresponding substantiallyto FIG. 25, but showing the lock-off button pushed inwardly and receivedwithin the pocket formed in the inner member, thereby locking the innermember and hence the blade in its retracted position.

FIG. 27 is a longitudinal sectional view, taken along the lines 27--27of FIG. 23 and drawn to an enlarged scale, and showing the inner memberbeing retracted into its normal position on the frame.

FIG. 28 is a further longitudinal sectional view, correspondingsubstantially to FIG. 27, but showing the inner member fully retractedwithin the frame and the lock-off button pushed inwardly and receivedwithin the pocket on the inner member, thereby locking the inner memberto the frame and preventing further movement of the inner memberrelative to the frame.

FIG. 29 is a perspective view of a further embodiment, whereby thelock-off button is carried by a depressible tang formed on a side wallof the frame.

FIG. 30 is an enlarged portion of FIG. 29, showing the lock-off buttonon the disposable tang being pushed inwardly of the frame and into thelocking position thereof

FIGS. 31-34 are schematic sequence drawings illustrating how theimproved blade of the central line kit avoids an inadvertent cut or nickof the patient's vein.

FIG. 31 illustrates, schematically, the prior art blade being positionedfor enlarging the puncture previously made in the patient's skin by theneedle.

FIG. 32 illustrates, schematically, how in the process of enlarging thepuncture in the patient's skin, the tip portion of the prior art blade(being fairly pointed) may inadvertently cut or nick the patient's veinbeneath the puncture in the skin.

FIG. 33 corresponds substantially to FIG. 31, but illustrates,schematically, the improved blade of the present invention beingpositioned for enlarging the puncture previously made in the patient'sskin by the needle.

FIG. 34 corresponds substantially to FIG. 32 but illustrates,schematically, how the tip portion of the improved blade of the presentinvention (being fairly blunt) will avoid an inadvertent cut or nick ofthe patient's vein in the process of enlarging the puncture in the skin.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1-3, the guarded finger scalpel 10 of thepresent invention includes a substantially rectangular frame 11 having atop wall 12, a bottom wall 13 and respective side portions 14 and 15having opening 16 and 17, respectively, formed therein. A pair of springarms 18 and 19 (or other resilient means) are confined between the topwall 12 and the bottom wall 13 of the frame 11, being disposedrearwardly of the frame 11 as shown in FIG. 3, and extend laterallythereof through the openings 16 and 17, respectively.

These spring arms 18 and 19 are bifurcated and, preferably, are formedfrom a single plastic moldment (as shown more clearly in FIG. 2) and arejoined together, first, at a forward portion 20 and, second, at arearward cap 21. The forward portion 20 of the spring arms 18, 19includes a longitudinally-extending lug 22 received within alongitudinal slotted opening 23 formed within a surgical blade 24. Thelug 22 may be swaged over the blade 24 and secured thereto (as shownmore clearly in FIGS. 2 and 3) by hot-staking or other productionprocess.

The blade 24 is slidably guided within a blade guide means 25 having anopening 26. The blade guide means 25 constitutes a guard means for theblade 24 and (in this embodiment) is substantially rectangular and isformed integrally with the frame 11, as for example, by a unitaryplastic moldment. Preferably, the blade guide means 25 is transparent,so that the blade 24 is visible at all times (even when the blade 24 isnormally confined therein).

The exposed faces of the laterally-extending spring arms are roughened,as at 27 in FIG. 1, to facilitate a manual grasping and manipulation ofthe guarded finger scalpel 10.

When the guarded finger scalpel 10 is thus grasped between the surgeon'sthumb and forefinger (FIG. 4), the spring arms 18, 19 are squeezedtogether (FIG. 5) laterally inwardly of the frame 11 to thereby advancethe blade 24 out of the opening 26.

Thus, the blade 24 of the guarded finger scalpel 10 of the presentinvention is only exposed while a cut or cuts are being made, therebysubstantially reducing (if not eliminating altogether) the risksassociated with using a conventional unguarded finger scalpel, not onlyin the highly-stressed environment of an operating room or critical careunit, but also in the subsequent clean up and disposal of the overallkit including the scalpel.

With reference again to FIG. 2, and with further reference to FIG. 6,the blade 24 and the spring arms 18 and 19 with their rearward cap 21constitutes a subassembly 28 or inner member nested with the frame 11.In the assembly of the guarded finger scalpel 10, the subassembly 28 isreceived through an opening 29 in a rear wall 30 of the frame 11. Thespring arms 18 and 19 are squeezed together to clear the opening 30, andthe spring arms 18, 19 are then released to enable the spring arms 18,19 to pass through the openings 16, 17 and laterally of the frame 11.The cap 21 is then seated against the rear wall 30 of the frame 11 andmay be secured thereby by protrusions (not shown) or by ultrasonicwelding, hot-staking or any suitable production process.

The guarded finger scalpel 10 comprises only three parts: the moldedframe 11, the molded spring arms 18 and 19, and the metal blade 24,respectively. Accordingly, the guarded finger scalpel 10 facilitateshigh-volume low-cost automated manufacture.

An alternate embodiment 10' of the guarded finger scalpel for thepresent invention is illustrated in FIGS. 7-10. This guarded fingerscalpel 10' has a resilient body 31, preferably of a suitable moldedplastic material, and being relatively small and easy to handle and toorient. Preferably, the body 31 has complementary halves 32 and 33,respectively, joined together along a common longitudinal midplane 34and suitably secured together, as for example, by ultrasonic welding.

A blade guide means or frame 35 is mounted within the resilient body 31,and a blade 36 is slidably guided within the frame 35. The blade 36 hasrespective sides 37 and 38; and a pair of spring arms 39 and 40,respectively, are connected between the sides 37, 38 and the resilientbody 31.

As the resilient body 31 is squeezed between the surgeon's thumb andforefinger, as shown in FIGS. 8 and 10, the respective spring arms 39and 40 deflect, that is, are compressed towards the frame 35; and as aresult, the blade 36 is advanced forwardly out of an opening 41 formedin the body 31.

Conversely, when the finger pressure is released, the respective springarms 39 and 40 return to their original position (FIGS. 7 and 9) and theblade 36 is again retracted within the body 31.

With this in mind, it will be understood by those skilled in the artthat the guard means is actively disarmed and moved from its normalposition into its retracted position when the guarded finger scalpel isgrasped. Conversely, the guard means is passively armed and returned toits normal position when the guarded finger scalpel is released.

The sides of the resilient body are indented, as at 42, to facilitatemanual manipulation of the guarded finer scalpel 10'.

Thus, with the guarded finger scalpels 10 and 10' of the presentinvention, the blades 24 and 36, respectively, are exposed only whenmaking a cut or cuts in the patient's skin. Otherwise, the blades 24, 36are covered at all times. Accordingly, the guarded finger scalpels 10and 10' of the present invention protect against inadvertent oraccidental nicks or cuts occasionally encountered by health careproviders (such as surgeons, nurses, technicians, operating roomassistants and clean-up personnel) and the serious health risksassociated therewith.

The protection also extends to the patient (or patients) if the surgeonor other health care provider is infected with HIV (the deadly AIDSvirus) or any other contagious disease. In the event an unguarded fingerscalpel becomes contaminated by tainted blood from the surgeon or otherhealth care provider, the disease may be inadvertently communicated tothe patient.

The protection afforded by the guarded finger scalpels 10 and 10' of thepresent invention, and the benefits and advantages of its improvedmethod, are illustrated in FIGS. 11-21.

In FIG. 11, a needle 100 is used to make a puncture 101 in a patient'sarm 102 to thereby locate a vein (for example). The needle 100 is an"introducer" needle. In some cases, it may be necessary to first use asmaller "starter" needle (not shown) to locate the patient's vein.Thereafter, a flexible guide wire 103 is inserted through the needle 100and through the puncture 101 (FIG. 12) and into the vein 104 (FIG. 13).The needle 100 is then removed and the guide wire 103 remains in thelumen, that is, within the opening in the vein, artery or intestine ofthe patient.

The guarded finger scalpel 10 (or 10') of the present invention isgrasped by the surgeon, usually between the surgeon's thumb andforefinger (FIG. 14), and is squeezed to advance the blade 24 (FIG. 15).The blade 24 is then used to make an incision or cut 105 in thepatient's skin (FIG. 16). One or more cuts 105 may be made, therebyenlarging the puncture 101 (and facilitating the subsequent insertion ofa catheter). Manual pressure is released to retract the blade 24, andthe guarded finger scalpel 10 is lifted away from the cut 105.

The blade 24 is no longer exposed, and the guarded finger scalpel 10 isthen discarded.

Thereafter, a catheter 106 (FIG. 18) is slipped over the guide wire 103and through the cut 105 (FIG. 19) and into the patient's vein 104 (FIG.20). Once the catheter 106 is in place, or while the catheter 106 isbeing inserted, the guide wire 103 is removed (as shown in FIG. 21).

This sequence of steps of the preferred method of using the guardedfinger scalpels 10 and 10' of the present invention is illustrated inthe schematic block diagram of FIG. 22.

With reference to FIGS. 23-28, the guarded finger scalpel 10 is providedwith a lock-off means 200. In this embodiment, the lock-off means 200includes a lock-off button 201 carried by a side portion or wall 14 ofthe guarded finger scalpel 10. This lock-off button 201, as shown moreclearly in FIG. 25, includes an enlarged head 202, a tapered body 203,and an enlarged foot 204, all of which, if desired, may be molded from asuitable plastic material. The lock-off button 201 may be pushed througha hole 205 in the side wall 14 and loosely retained therein between theenlarged head 202 and the enlarged foot 204. The enlarged head 202 maybe roughened or knurled, as at 206 in FIG. 24, to facilitate aconvenient manipulation thereof.

The forward portion 20 of the inner member (comprising the respectivespring arms 18 and 19) has a blind pocket 207 formed therein. This blindpocket 207 is preferably tapered inwardly thereof and has an internalannular shelf 208 formed therein, as shown more clearly in FIG. 25.

When the surgical procedure of installing a line in a patient has beencompleted, and no further use of the guarded finger scalpel 10 isrequired, the lock-off button 201 may be pushed inwardly thereof (FIG.24) so that its enlarged foot 204 is "popped" into the blind pocket 207and is received firmly therein, as shown more clearly in FIG. 26. Theforward portion 20 of the inner member is thereby locked to the frame11.

Thereafter, the blade 24 cannot extend beyond the guard 25 even if therespective spring arms 19 and 20 (or one of them) is squeezedinadvertently or accidentally. This feature is very desirable inpreventing nicks or cuts to the surgeon, nurse, technician or clean-uppersonnel while disposing of the guarded finger scalpel 10 and itsoverall kit. Thus, the guarded finger scalpel 10 of the presentinvention is provided, not only with a guard for protection whileinstalling a line, trocar or similar medical device in a patient, but isalso provided with the lock-off means 200 for protection during disposaland clean-up.

With reference to FIGS. 29 and 30, a lock-off button 209 may be moldedintegrally with a depressible tang 210 formed by a pair of parallelslots 211 and 212, respectively, in the side wall 14 of the guardedfinger scalpel 10.

With reference to FIGS. 31-34, the kit of the present invention includesan improved blade on the guarded finger scalpel, thereby preventingaccidental nicks or cuts in the patient's arm while using the guardedfinger scalpel to enlarge the puncture in the patient's skin (thepuncture being previously made by the needle in the kit).

FIGS. 31 and 32 illustrate, schematically, the problem occasionallyencountered in the prior art. The blade 24 has a forward portion with afairly pointed tip 300, and the acute angle A formed between the loweredge 301 and the front edge 302 is approximately 30°. This blade 24 istypically referred to in the art as a "No. 11 Blade" and is usedextensively in central line kits.

As a result of this pointed tip configuration, it is not at all unusualfor the blade 24 to inadvertently or accidentally pierce (or nick orcut) the patient's vein 104 in the process of enlarging the puncture 105(as illustrated in FIG. 32).

To avoid this problem, and as shown in FIG. 33, the improved blade 303of the present invention has a forward portion which is less pointed andmore blunt than that of the prior art blade 24. The acute angle Bdefined between the lower edge 304 and the front edge 305 is more than45° and, in the preferred embodiment, approximately 60°.

As a result of the tip configuration of the improved blade 303 of thepresent invention, and as shown in FIG. 34, the possibility ofinadvertently or accidentally cutting or nicking the patient's vein 104is substantially reduced (if not eliminated altogether).

Obviously, many modifications may be made without departing from thebasic spirit of the present invention. For example, instead of thepatient's vein (as shown herein) the flexible guide wire 103 may beinserted into a patient's organ, vessel or body cavity under certaincircumstances during a surgical procedure. Also, the guarded fingerscalpel may be used by any health care provider, such as a cardiologist,pulmonary doctor, anesthesiologist, nurse, etc. Accordingly, it will beappreciated by those skilled in the art that within the scope of theappended claims, the invention may be practiced other than has beenspecifically described herein.

We claim:
 1. In a kit for a central line to be installed in a patient,the combination of a needle for making a puncture in the patient's skinabove one of the veins, a guarded finger scalpel having a blade attachedthereto for enlarging the puncture in the patient's skin, guard means onthe guarded finger scalpel, the guard means having a normal position inwhich the blade is covered and further having a retracted position inwhich the blade is exposed, the blade having a planar body provided witha top edge and a lower cutting edge, and the blade terminating forwardlythereof in a tip portion defined by a front edge connecting the top edgeof the blade with the lower cutting edge of the blade, the front edgeand the lower cutting edge forming an acute angle therebetween, theacute angle being sufficiently large to prevent the blade from cuttinginto the vein adjacent to the puncture in the patent's skin, and whereinthe guard means does not contact the lower cutting edge of the bladeduring relative movement between the guard means and the blade, therebyavoiding an inadvertent dulling of the lower cutting edge of the blade.2. The combination of claim 1, wherein the acute angle is greater than45°.
 3. The combination of claim 2, wherein the acute angle isapproximately 60°.
 4. The combination of claim 1, wherein the guardmeans is actively disarmed and moved from its normal position into itsretracted position when the guarded finger scalpel is grasped and isfurther passively armed and returned to its normal position when theguarded finger scalpel is released.
 5. The combination of claim 1,wherein the guarded finger scalpel includes a body normally intended tobe grasped between the surgeon's thumb and forefinger, the bodycomprising a frame including a pair of side walls having respectiveopenings therein, wherein an inner member is confined within the frameand is guided for slidable movement therein, the inner member carryingthe blade thereon, and the guard means comprising at least one springarm carried by the inner member and extending through a respectiveopening in the frame.
 6. The combination of claim 1, further including alock-off means operative in the normal position of the guard means andpreventing movement of the guard means from its normal position into itsretracted position, thereby preventing blade exposure and protecting theclean-up personnel in the hospital against inadvertent nicks or cutsduring disposal of the kit.
 7. (amended) In a kit for a central line tobe installed in a patient, the combination of a needle for making apuncture in the patient's skin above one of the veins, a guarded fingerscalpel having a blade attached thereto for enlarging the puncture inthe patient's skin, guard means on the guarded finger scalpel, the guardmeans having a normal position in which the blade is covered and furtherhaving a retracted position in which the blade is exposed, the guardmeans being actively disarmed and moved from its normal position intoits retracted position when the guarded finger scalpel is grasped andfurther being passively armed and returned to its normal position whenthe guarded finger scalpel is released, a lock-off means operative inthe normal position of the guard means and preventing movement of theguard means from its normal position into its retracted position,thereby preventing blade exposure and protecting the clean-up personnelin the hospital against inadvertent nicks or cuts during disposal of thekit, the blade having a planar body provided with a top edge and a lowercutting edge, and the blade terminating forwardly thereof in a tipportion defined by a front edge connecting the top edge of the bladewith the lower cutting edge of the blade, the front edge and the lowercutting edge forming an acute angle therebetween, the acute angle beingapproximately 60° to prevent the blade from cutting into the veinadjacent to the puncture in the patient's skin, and wherein the guardmeans does not contact the lower cutting edge of the blade duringrelative movement between the guard means and the blade, therebyavoiding an inadvertent dulling of the lower cutting edge of the blade.